The present invention relates to an apparatus for irradiating material by an electron beam. Such apparatus is useful in a number of diverse areas such as for the sterilization of food products, the polymerization of monomers and for genetic purposes such as for the irradiation of seeds and insects. Although such devices are extremely useful, the high currents and high voltages which are employed in providing an appropriate electron beam of suitable intensity has generally mandated the providing of multiple enclosures some of which are placed under either high vacuum and/or high gas pressure. Logistically, these various enclosures occupy surprisingly large volumes which makes the implementation of electron beam irradiators cumbersome at best.
FIG. 1 typifies prior art electron beam irradiation sources and their supporting power supplies. Specifically, an enclosure 10 for a high voltage power supply 11 is provided having high voltage cable connectors 1 connecting enclosure 10 to enclosure 20 via a single conductor high voltage cable 12. Enclosure 20 which is generally provided at high gas pressure is again a high voltage enclosure for electron beam gun control elements 2 and a high voltage isolation transformer 3 for the cathode heater 5 and auxiliary power for control elements 2. High gas pressure enclosure 20 is connected to an electron beam gun vacuum chamber 30 via gas to vacuum high voltage bushing 4. Each of these elements are well known to those skilled in this art.
The high power hot cathode electron beam gun's cathode heater 5 housed in enclosure 30 requires a high current, in the order of at least 100 amps, from its power source. It has been universally recognized that this source must be located close to the electron beam gun because the high voltage cable, to which the cathode is connected, cannot carry such high currents. The cathode is floating at a very high potential, typically 200-300 kV, and, therefore, the heater current source is also floating at the same high voltage. As noted by reference to FIG. 1, in a conventional design, the current source is contained in a special tank or enclosure 20 located between the gun end of the high voltage cable and the gun itself. This tank being at least approximately the same size as the gun enclosure, is expensive and occupies a large space in the electron beam processor production area.
It is thus an object of the present invention to provide an electron beam gun assembly which, by virtue of its design, is capable of eliminating the special tank between the gun end of a high voltage cable and the gun itself.
It is yet another object of the present invention to provide a high voltage cable termination with built-in current matching transformer which would provide for the complete elimination of a high voltage tank assembly and high voltage bushing.